From e06561317391d76d67a1052b755ce366ba151aa2 Mon Sep 17 00:00:00 2001
From: Takumi Shotoku <sinsoku.listy@gmail.com>
Date: Wed, 18 Sep 2024 23:08:04 +0900
Subject: [PATCH] Ensure that generics parameters are set in Array and Hash

The RBS generated by rbs-inline does not have generics for Array and
Hash, so `rbs validate` will fail.

```ruby
# example.rb
class A
  FOO = []
  BAR = {}
end
````

```console
$ rbs-inline --opt-out --output example.rb
$ rbs -I sig validate

E, [2024-09-18T23:35:08.624066 #79451] ERROR -- rbs: sig/generated/example.rbs:4:7. .4:14: ::Array expects parameters [unchecked out Elem], but given args [] (RBS::InvalidTypeApplicationError)
E, [2024-09-18T23:35:08.624103 #79451] ERROR -- rbs: sig/generated/example.rbs:6:7. .6:13: ::Hash expects parameters [unchecked out K, unchecked out V], but given args [] (RBS::InvalidTypeApplicationError)
````

Add untyped generics parameters to avoid validation errors.
---
 lib/rbs/inline/writer.rb            | 24 +++++++++++++++++++++++-
 sig/generated/rbs/inline/writer.rbs |  7 +++++++
 test/rbs/inline/writer_test.rb      | 14 ++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/lib/rbs/inline/writer.rb b/lib/rbs/inline/writer.rb
index 276c851..391b24e 100644
--- a/lib/rbs/inline/writer.rb
+++ b/lib/rbs/inline/writer.rb
@@ -180,7 +180,7 @@ def translate_constant_decl(decl, rbs)
 
         rbs << RBS::AST::Declarations::Constant.new(
           name: decl.constant_name,
-          type: decl.type,
+          type: constant_decl_to_type(decl),
           comment: comment,
           location: nil
         )
@@ -608,6 +608,28 @@ def translate_class_block_decl(block, rbs)
           comment: comment
         )
       end
+
+      # @rbs decl: AST::Declarations::ConstantDecl
+      # @rbs return: RBS::Types::t
+      def constant_decl_to_type(decl)
+        type = decl.type
+        return type unless type.is_a?(RBS::Types::ClassInstance)
+        return type if type.args.any?
+
+        case decl.node.value
+        when Prism::ArrayNode
+          RBS::BuiltinNames::Array.instance_type(untyped)
+        when Prism::HashNode
+          RBS::BuiltinNames::Hash.instance_type(untyped, untyped)
+        else
+          type
+        end
+      end
+
+      # @rbs return: RBS::Types::Bases::Any
+      def untyped
+        @untyped ||= RBS::Types::Bases::Any.new(location: nil)
+      end
     end
   end
 end
diff --git a/sig/generated/rbs/inline/writer.rbs b/sig/generated/rbs/inline/writer.rbs
index 0d3ea2b..ab52410 100644
--- a/sig/generated/rbs/inline/writer.rbs
+++ b/sig/generated/rbs/inline/writer.rbs
@@ -107,6 +107,13 @@ module RBS
       # @rbs rbs: _Content
       # @rbs return: void
       def translate_class_block_decl: (AST::Declarations::BlockDecl block, _Content rbs) -> void
+
+      # @rbs decl: AST::Declarations::ConstantDecl
+      # @rbs return: RBS::Types::t
+      def constant_decl_to_type: (AST::Declarations::ConstantDecl decl) -> RBS::Types::t
+
+      # @rbs return: RBS::Types::Bases::Any
+      def untyped: () -> RBS::Types::Bases::Any
     end
   end
 end
diff --git a/test/rbs/inline/writer_test.rb b/test/rbs/inline/writer_test.rb
index 5842f53..a8da368 100644
--- a/test/rbs/inline/writer_test.rb
+++ b/test/rbs/inline/writer_test.rb
@@ -482,6 +482,20 @@ def test_constant_decl
     RBS
   end
 
+  def test_constant__without_decl
+    output = translate(<<~RUBY)
+      TAGS = []
+
+      OPTIONS = {}
+    RUBY
+
+    assert_equal <<~RBS, output
+      TAGS: ::Array[untyped]
+
+      OPTIONS: ::Hash[untyped, untyped]
+    RBS
+  end
+
   def test_generic_class_module
     output = translate(<<~RUBY)
       # @rbs generic T